-er a-a a-b a-c aaa aab aac aae aaf aah aar ab- aba abb abc abe abf abh abr ac- aca acb acc ace acf ach acr aea aeb aec aee aef aeh aer af- afa afb afc afe aff afh afr aha ahb ahc ahe ahf ahh ahr ar- ara arb arc are arf arh arr baa bab bac bae baf bah bar bba bbb bbc bbe bbf bbh bbr bca bcb bcc bce bcf bch bcr be- bea beb bec bee bef beh ber bfa bfb bfc bfe bff bfh bfr bha bhb bhc bhe bhf bhh bhr bra brb bre brf brh brr c-- caa cab cac cae caf cah car cba cbb cbc cbe cbf cbh cbr cca ccb ccc cce ccf cch ccr ce- cea ceb cec cee cef ceh cer cfa cfb cfc cfe cff cfh cfr ch- cha chb chc che chf chh chr cra crb crc cre crf crh crr eaa eab eac eae eaf eah ear eba ebb ebc ebe ebf ebh ebr ec- eca ecb ecc ece ecf ech ecr eea eeb eec eee eef eer ef- efa efb efc efe eff efh efr eha ehb ehc ehe ehf ehh ehr era erb erc ere erf erh err faa fab fac fae faf fah far fba fbb fbc fbe fbf fbh fbr fca fcb fcc fce fcf fcr fea feb fec fee fef feh fer ffa ffc ffe fff ffh ffr fha fhb fhc fhe fhf fhh fhr fra frb frc fre frf frh frr haa hab hac hae haf hah har hba hbb hbc hbe hbf hbh hbr hca hcb hcc hce hcf hch hcr he- hea heb hec hee hef heh her hfa hfb hfc hfe hff hfh hfr hha hhb hhc hhe hhf hhh hhr hr- hra hrb hrc hre hrf hrh hrr ra- raa rab rac rae raf rah rar rba rbb rbc rbe rbf rbh rbr rca rcb rcc rce rcf rch rcr re- rea reb rec ree ref reh rer rfa rfb rfc rfe rff rfh rfr rh- rha rhb rhc rhe rhf rhh rhr rra rrb rrc rrf rrh rrr